Ars has reviewed GNOME 2.20. "GNOME 2.20 was officially released last week after six months of development. The new version includes strong incremental improvements that contribute to a better user experience and provide more flexibility and integration opportunities for third-party software developers."

Gnome includes Tomboy:
from their news section: Tomboy: Stable version 0.6.1 released! This will be the version included by GNOME 2.18.0.
If Gnome includes tomboy, then gnome becomes dependent on any of its sub packages, and thus its dependent on mono.